Pneumatic tire with tread having non-linear rib

Abstract

A pneumatic tire comprises a tread portion provided with a nonlinear rib having an amplitude having a center in the tire axial direction. In a normally loaded condition of the tire, the tread portion has an outside tread edge and an inside tread edge when the camber angle of the tire is 0 degrees. In the normally loaded condition, when the a camber angle of 4 degrees is given to the tire to inline towards the outside tread edge, a foot print shape of the tire has a maximum circumferential length at an axial position MC which is off the tire equator towards the outside tread edge. The nonlinear rib is positioned off the tire equator towards the outside tread edge such that the axial position MC lies within the amplitude of the nonlinear rib, and one of the edges of the nonlinear rib on the outside tread edge side is chamfered.

1. A pneumatic tire comprising a tread portion provided with a nonlinear rib having an amplitude having a center in the tire axial direction, wherein
 in a normally loaded condition of the tire, the tread portion has an outside tread edge Eo and an inside tread edge Ei when the camber angle of the tire is 0 degrees, 
 in said normally loaded condition, when a camber angle of 4 degrees is given to the tire to incline towards the outside tread edge Eo, a foot print shape of the tire has a maximum circumferential length at an axial position MC which is off the tire equator towards the outside tread edge Eo, 
 said nonlinear rib is positioned off the tire equator towards the outside tread edge Eo such that said axial position MC lies within the amplitude of the nonlinear rib, and 
 one of the edges of the nonlinear rib on the outside tread edge side is chamfered, 
 wherein the tread portion is further provided with 
 an outside nonlinear circumferential groove disposed on the outside tread edge side of said nonlinear rib adjacent to the nonlinear rib, 
 outside main lateral grooves extending from the outside nonlinear circumferential groove to the outside tread edge Eo, wherein edges of each said outside main lateral grooves are chamfered, at least in the vicinity of the outside tread edge Eo, and 
 outside secondary lateral grooves disposed between the outside main lateral grooves and extending from said outside nonlinear circumferential groove towards the outside tread edge Eo but terminates before the outside tread edge Eo, wherein the outside secondary lateral grooves are provided therein with tie-bars. 
 
   
   
     2. The pneumatic tire according to  claim 1 , wherein the axial distance of the center of the amplitude from the axial position MC is not more than 40% of the amplitude. 
   
   
     3. The pneumatic tire according to  claim 1 , wherein the axial distance of the center of the amplitude from the axial position MC is less than 5% of the amplitude. 
   
   
     4. The pneumatic tire according to  claim 1 , wherein
 the tread portion is further provided with an inside main nonlinear circumferential groove and an inside secondary nonlinear circumferential groove more linear than the inside main nonlinear circumferential groove, 
 the inside main nonlinear circumferential groove disposed on the inside tread edge side of said nonlinear rib adjacently to the rib, and 
 the inside secondary nonlinear circumferential groove disposed between said inside main nonlinear circumferential groove and said inside tread edge Ei. 
 
   
   
     5. The pneumatic tire according to  claim 1 , wherein
 in a normally inflated unloaded condition of the tire, a tread camber D measured at the outside tread edge is in a range of not less than 0.04 and not more than 0.06 times the tread width TW measured between the outside and inside tread edges.